Ecology of the Chinese stripe-necked turtle, Ocadia sinensis (Testudines: Emydidae), in the Keelung river, Northern Taiwan

An intensive ecological study of a large population of the Chinese stripe-necked turtle, Ocadia sinensis, was conducted in northern Taiwan from February 1995 to May 1996. Of 661 turtles captured and measured, there were 136 unsexed juveniles, 289 males, and 233 females; the sex ratio was significantly male-biased. Significant sexual size dimorphism was evident. Females grew larger than males; mean body size of females over four years was consistently larger than that of coeval males. X-ray photography revealed that females were gravid from March to May. Clutch size averaged 12.6 and varied from 7 to 17. Stomach contents collected from June to October 1995 revealed sexual differences in diet: males tended to consume animal matter, whereas females exhibited a dietary shift from carnivory to herbivory during growth from juvenile to adult.